4. , 2 , , 90, ( ), 4 , , , . , 630 , 5 .
. , h 5 . , Dh, .
(9)
h2minN=2pLNl. (10)
,
h2minN+1-h2minN=(hminN+Dhmin)2-h2minN2 hminN×Dhmin. (11)
(10) :
h2minN+1-h2minN=2pLl. (12)
(10) - (12) :
hminN×Dhmin=pLl, (13)
(14)
5. . ?